This document summarizes research on water quality and gastrointestinal illness from two case studies. The first case study examined water contamination between the source and point of use in Esmeraldas, Ecuador. It found higher levels of E. coli and enterococci at the source than in household water, along with recontamination occurring in about 50% of households. The second case study analyzed the relationship between water residence time in the distribution system and gastrointestinal illness in Atlanta, GA. It found that people in zip codes receiving water with the longest residence times had a moderately increased risk of GI illness. Both studies suggest considering initial water quality and potential for recontamination.

1. Karen Levy, PhD, MPH
October 2013
Salúd Ambiental en Chile: Orientación para Futuras
Investigaciones
Planning for a GeoHealth Hub in Chile
Agua Potable y Enfermedades
Gastrointestinales en Esmeraldas,
Ecuador y Atlanta, GA

2. •Overview of contamination between
source and point of use
•Case Study from Esmeraldas, Ecuador
•Case Study from Atlanta, GA
Agua Potable y Enfermedades
Gastrointestinales en Esmeraldas,
Ecuador y Atlanta, GA

3. Storing water
Deterioration of
water quality

4. Higher water quality observed at the
source than at the point of use
Wright et al. 2004. Tropical Medicine & International Health 9(1): 106-117

5. •Case Study from Esmeraldas, Ecuador

6. Study Region

7. bathing

8. washing

9. 1°
water
source
is
surface
water
collec.ng
water

10. Xt=0
Point
of Use
xPOU, t=1, xPOU, t=2, …xPOU, t=n
Source
Controlled
Env’t
xcontrol, t=1, xcontrol, t=2, …xcontrol, t=n

11. Agua almacenado en la casa

12. Muestras de agua de la fuente

13. Recipientes Controles

14. testing for e.coli & enterococci in the field

15. N Enterococci
CFU/100mL
E.coli
CFU/100mL
Source 59 227.9 227.1
(139.5 – 372.4) (144.6-356.9)
Household 105 103.7 113.4
(70.7-152.1) (80.8-159.0)
Control 105 80.8 83.8
(54.3-120.1) (57.8-121.5)
Contamination:
Source > Point of Use
Contaminación Observada

16. Paired log differences:
Natural attenuation = Source – Control
In-home attenuation = Source – Household
In-home recontamination = Household - Control
Enterococci E.coli
(GEE regressions adjust for clustering by paired household samples,
and to account for autocorrelation between sampling days) n=105

17. Findings
Reductions of indicator organisms between source and POU…
…followed by recontamination in ~50% of households
Levy et al. 2008. Environmental Health Perspectives
116(11): 1533-1540.
This suggests the need to consider both initial water
quality conditions and recontamination

18. •Case Study from Atlanta, GA

21. • Does water degradation in the distribution
system contribute to sporadic GI illness?

22. Source: Besner et al. 2011 Water Research 45: 961-979

23. Source: Besner et al. 2011 Water Research 45: 961-979
ER visits

24. Gastrointestinal Disease Data
• 41 hospitals in Metro Atlanta
• 4.4 million ED records
• 254,760 GI illness records
(based on ICD-9 codes)
• Non-injury visits = comparison
group
• Address + zip-code data for
majority of records

25. Water Utility Data
• Hydraulic Models
• Utility Coverage Areas
• Water Residence Time from plant to node
(estimated through simulations of water
flow through the distribution system)

26. Source: Besner et al. 2011 Water Research 45: 961-979
Water
Residence
Time
ER visits

27. Utility 1 Utility 2
WRT: short 6.8 /intermediate 22.0 / long 47.4 hrs
WRT: short 10.1 / intermediate 33.4 / long 74.4 hrs
WRT: short 5.9 / intermediate 18.5 / long 60.4 hrs

28. ControlVariables
(Census Data & ED records)
• Age
• Season
• Year
• Hospital
• Distance from zip code centroid to hospital
• Zip code median income
• Zip code percent minority
• Medicaid payment status
• Age*Medicaid
• Age*Distance to hospital
• Medicaid*Distance to hospital

29. OddsRatio
Based onTinker et al. 2009. JWH 7(2): 332-343
.85
.85
.85.95
.95
.951.05
1.05
1.051.15
1.15
1.150
0
0.5
.5
.51
1
11.5
1.5
1.52
2
20
0
0.5
.5
.51
1
11.5
1.5
1.52
2
2Utility 1
Utility 1
Utility 1Utility 2
Utility 2
Utility 2Zipcode WRT, All addresses, 28 hospitals
Zipcode WRT, All addresses, 28 hospitals
Zipcode WRT, All addresses, 28 hospitalscomparison_no
comparison_no
comparison_no
Water Residence Time
Short Intermediate Long Short Intermediate Long
OR = 1.05
(1.00-1.09)
OR = 1.05
(1.02-1.08)

30. Conclusions:
• People living in zip codes receiving water
with the longest residence time in the
distribution system may be at moderately
increased risk for GI illness

31. Follow-up Study to Evaluate
Microbial Water Quality in the
Distribution System
• Water Residence Time
• Main Breaks
• Pressure Fluctuations

35. Monitoring
Locations

36. Automated Monitoring and
Sampling (AMS) Device

37. Ultrafiltración para
Muestras de GranVolumen
Recycle
Pump
Sample
reservoir100 L
Ultrafilter
Air vent
Retentate
reservoir
Q Permeate (waste)
Flow
Flow
Restrictor
Dead-end
Flow meter
1L
2,900 mL/min
1
,
2
1,100 mL/min
3-way valve

38. Water
Sample!
Filtered Water!
(aka “filtrate” or “permeate”)!
(UF Membrane)!
Microbes!
Suspended solids!
Colloidal matter!
Large dissolved molecules!
Hollow Fiber Ultrafiltration Schematic
Division of Foodborne,Waterborne and
Environmental Diseases at the CDC in
Atlanta with Dr.Vincent Hill!

39. Microbiological Analysis
Membrane
Filtration
~400 ml
Concentrate + Back flush
PEG
0.1 mL 1 mL 10 mL
E. coli; Total coliforms; C. perfringens;
HPC; P. aeruginosa; A. hydrophila
60 to 100 mL
Actual volume filtered for each
Standard Methods for the Examination of Water and Wastewater; 20th Edition, 1999 American Public Health Association Publications
Sample Collection
AMS (90L) or Grab sample (2L)
Ultrafiltration
(AMS, 90L)
100 mL
10^3 10^4 10^5
25 ml actual volume pour plate each
Male-specific (MS2) and Somatic
Coliphage
Dr. Nick Ashbolt lab
Mycobacterium avium
complex (MAC),
Legionella +amoebae,
Cryptosporidium

41. 1 2 3 4 5 6
0
0. 5
1. 0
1. 5
2. 0
E
.
c
o
l
i
C
F
U
/
1
0
0
m
l
Si t e

42. Acknowledgements
• Funding: EPA-STAR grant #R834250
(PIs Christine Moe & Paige Tolbert)
• Co-Authors: Mitch Klein, Stefanie Sarnat, Sarah
Tinker, Samina Panwhar, Alexandra Huttinger,
Jim Uber, Paige Tolbert, Christine Moe
• Other:Water Utility staff, Hospital staff
R834250
The content of this presentation is solely the responsibility of the grantee
and does not necessarily represent the official views of the US EPA

43. Co-­‐Authors:
• Kara
Nelson
• Alan
Hubbard
• Joe
Eisenberg
Field
Assistance:
• Sarah
Bates
• Sangam
Tiwari
• Laura
McLaughlin
• Karina
Ponce
• Patricio
Bueno
• William
Cevallos
• Geovanny
Hurtado
• Maritza
Renteria
• Deni
Tenorio
• Jairo
Ayovi
• Mirta
Campaz
• Melecio
Quintero
• Owen
Solberg
• Khalid
Kadir
ACKNOWLEDGEMENTS
Funding:
• NIAID
Grant
#RO1AI050038
• UCOP
Pacific
Rim
Research
Program

44. gracias.

45. Good
San
Good WQ
Bad WQ
Bad
San
Highest potential for
recontamination
High potential for
recontamination
Intermediate potential
for recontamination
Lowest potential for
recontamination
improve water
storage &
sanitation
improve water
storage
integrated
approach
improve wq +
water storage

46. Other Water Sources
rainwater
harvesting
piped surface
water
private
wells